Sorry you're going through this. If you search this forum, you'll see a lot of threads on thrush, and there tend to be a few common schools of thought:
1. A bleach solution approach- many swear by it, some fear it will cause damage to healthy tissue.
2. Natural products like apple cider vinegar (ACV) or raw honey- rinsing with diluted ACV, and then smearing on honey (or packing hoofs with honey-soaked cotton). They don't need to be used together, some use one vs. the other, some use both.
3. "Over the counter" products like Thrush Buster or other liquids like what you're describing above (though sorry, I don't know the name of the product you're describing).
4. Dry Thrush products, like "No Thrush
"-this is a dry, powdered product in a bottle that squirts into cracks and crevices. The reasoning is that if thrush is made worse by damp, moist conditions, why would you want to add more moisture.
5. "Pete's Goo
"- a mixture of human athlete's foot cream (you need the "Lotrimin" type or generic) and antibiotic ointment (in a 1:1 ratio) that you mix up yourself, stuff into an empty syringe, and then load into cracks.
Personally, I've had thrush problems on and off for months with my mare. I tried the ACV, honey, and liquid over the counter treatments like Thrush Buster and saw no real improvement. I had periods when the No Thrush did seem to help, and I find that useful for preventative maintenance, but it's not universal. I have been using the Pete's Goo in the past two weeks and am actually seeing good results. I have personally avoided bleach-based solutions as I'm leery of hurting healthy tissue, though again, many here swear by it.
Underlying all of this is your horse's nutrition and diet. I am not an expert in that, so will not comment, except to say there really is a connection and you need to be sure diet is in order to support healthy feet.
I am neither a vet nor a farrier, so if you have a severe case, I would definitely urge you to talk with either of them so they can advise you on your horse. Good luck researching your options and helping your horse!